The driver stopped in Surrey, outside of London, and called emergency services after hearing loud banging coming from inside the truck.

When police opened the truck’s doors, 15 Iraqi, Iranian, Syrian and Kurdish migrants spilled out, shivering after being holed up inside the truck where temperatures were 13 degrees below zero, the BBC reported.

"They have got a lot of sleeping bags in there -- they must have huddled together to keep warm," said Inspector Alan Nicholls.

Police said the youngest passenger was 13 years old and three who were suffering from hypothermia were taken to local hospitals for treatment.

All the passengers were detained on suspicion of illegal entry and the minors inside the truck will be given to the care of social services.

The truck driver is assisting police with the investigation, which will be handed over to the UK Visas and Immigration service, Sky News reported.

Authorities suspected that the group boarded the truck early Friday before it passed through the Channel Tunnel, the BBC reported.